Electronic color production hardware and software systems currently exist which separately and independently perform tasks associated with production of color-related products. For example, a known system reads a visible spectrum of a color sample and generates data regarding measured amounts of light absorbed or reflected at particular points in the spectrum. Any given color has a spectral curve associated with it that functions as a signature of the color. Once a spectral curve is determined, the visible spectrum and coefficients are then processed to predict a color formula for reproducing the color. The color formula can then be analyzed, for example, to create a color ink formula for creating a colored object.
Other common color representations exist, for example RGB represents the degree of red, green and blue in a color. CMYK represents the degree of cyan, magenta, yellow and black in a given color Accurate translation between color representations, for example a translation from RGB to CMYK for computer monitors and computer printers is provided by various software applications. Accurate color reproduction is achieved, in part, by retrieving data for a plurality of input and output devices, e.g., printers, monitors, and color measuring devices, and modifying the color translation formulas to account for the specific devices receiving the data. Computer software design packages, such as ADOBE ILLUSTRATOR and PAGEMAKER, provide such conversion functionality. Another known system provides a method and apparatus for accurately matching colors. For example, spectral data are received from a color measuring device and the corresponding color is matched in an electronic color library. The desired color is compared to colors stored in the electronic color library and the color or colors in the library that are within a specified color range are reported. By searching in an electronic library, the traditional standard color swatch book used for locating a desired color is replaced. This electronic color library is vulnerable, however, to problems associated with reproducing samples from multiple devices.
Another method involves receiving a communication of the designer's computer image and converting the RGB setting to CIELAB values. Computer software design packages such as ADOBE PHOTOSHOP provide such conversion functionality.
Methods exist for defining color ink formulas for making ink suitable for creating a particular color on two or more particular substrates or materials. For example, an ink formula is known to produce a particular shade of blue on corrugated cardboard. A different ink formula is known to produce the same shade of blue on aluminum. Problems are known to occur, however, with respect to metamerism. In such a case, while the two shades of blue in the above example appear identical in one lighting environment, the shades appear different in a second lighting environment. Problems associated with metamerism are known to increase with respect to specific colors, such as light purples, grays, tans, browns and blues. Moreover, the types of inks used to manufacture products can impact the degree of metamerism. For example, when the color of the label is required to match the pigmented plastic of a container, pigmented inks tend to minimize the changes in appearance caused by metamerism, while dye based inks will appear differently under differing lighting conditions. Inks, normally printed over a white or metallic substrate as a transparent film, will exhibit some metamerism compared to the identical pigment mixed with a white pigment, such as is the common practice in structural plastics or opaque paint films.
Another example of a problem associated with metamerism is caused by different dye lots used to create a colored product. For example, a strip of cloth that contains dye from two different dye lots may appear the same under specific lighting conditions, and different in other lighting conditions. The respective dye lots can reflect and absorb different light wavelengths somewhat differently, thereby causing the appearance of cloth to vary under different lighting conditions. See, for example, Metamerism and Metameric Pairs, M. David Stone, Jun. 9, 2001 (published to www.extremetech.com).
In commercial settings, undesirable effects caused by metamerism can be expensive and significant. Products may have to be remade or modified due to undesired appearances caused by metamerism in order to comply with customer demands. The ramifications of customer dissatisfaction caused by metamerism can result in high financial costs. Commercial vendors of computer color matching software, such as Datacolor International, GretagMacbeth, or X-Rite, all offer some form of color and formula storage and retrieval processes, often termed a palette. But these options are available for only a single product application (a single ink palette, a single plastics palette or a single textile palette). Using the separate palettes requires optimizing to an external standard. Two optimized matches to an external standard may not exhibit the optimum match to each other, leaving the final product with an objectionable color mismatch.